Support case insensitive URL pattern

[giginet]

According to RFC-3986, URL must be case-insensitive.

When opening App from capital-cased URL Scheme, Currently, Crossroad couldn't handle them.

router.register("myapp://users/:id", { return true })
router.openIfPosible(URL(string: "MYAPP://USERS/10"))!

Crossroad 3 can treat URL as case insensitive.
And remove caseInsensitive options from Context.